A polytetrafluoroethylene-coated glass fiber cloth and a method for manufacturing the same

Abstract

The application provides a polytetrafluoroethylene-coated glass fiber cloth and a preparation method thereof, and belongs to the technical field of glass fiber cloth modification. The fiber diameter, yarn twist and weaving density of the glass fiber base cloth are controlled to reduce the porosity and surface roughness from the structure, and the uniformity of the polytetrafluoroethylene dispersion liquid is improved. Meanwhile, the fluorine-containing surface active leveling agent is added to reduce the surface tension of the dispersion liquid, improve the spreading ability of the coating, reduce the accumulation and defect phenomenon, the micro-nano closed / skeleton modifier is added to fill the pores of the fiber base cloth, limit the excessive penetration of the dispersion liquid, and form a stable micro-nano skeleton structure in the sintering process, thereby enhancing the mechanical strength and wear resistance of the coating. The two additives synergistically act on the surface and internal structure of the coating from the aspects of 'flow-spreading' and 'closure-skeleton', not only reducing the amount of polytetrafluoroethylene, but also improving the uniformity, heat resistance and mechanical properties of the coating.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of glass fiber cloth modification, and relates to a polytetrafluoroethylene coated glass fiber cloth and a preparation method thereof. BACKGROUND

[0002] Polytetrafluoroethylene is an ideal material in many industrial fields due to its excellent high-temperature resistance, corrosion resistance and excellent insulation performance, especially in environments with extremely high requirements for material performance such as chemical industry, electronics and aerospace. The unique properties of polytetrafluoroethylene enable it to maintain stable performance under extreme conditions, thereby effectively protecting the substrate and prolonging its service life. In this context, the application of polytetrafluoroethylene coating to glass fiber cloth can improve its mechanical strength and chemical resistance, making it more suitable for use in harsh conditions.

[0003] Traditional polytetrafluoroethylene coating methods usually use immersion method to directly immerse the glass fiber base cloth in the polytetrafluoroethylene solution for coating. Although this method is simple and easy to implement, it has some shortcomings in actual application. First, when the glass fiber base cloth is immersed in polytetrafluoroethylene, it often leads to excessive use of polytetrafluoroethylene. This not only causes waste of materials and increases production costs, but also may result in unevenness of the coating, thereby affecting the performance and appearance of the final product.

[0004] Secondly, excessive polytetrafluoroethylene coating may result in uneven coating thickness, reducing the adhesion and durability of the material. Thick coating is prone to peeling, cracking and other phenomena during use, which reduces the effectiveness of the glass fiber cloth in high-temperature and corrosive environments. These problems make it difficult for traditional polytetrafluoroethylene coating technology to meet the strict requirements of modern industry for high-performance composite materials, so it is urgent to develop more efficient and economical coating methods. SUMMARY

[0005] To solve the above problems, the present application provides a polytetrafluoroethylene coated glass fiber cloth and a preparation method thereof. The present application controls the fiber diameter, yarn twist and weaving density of the glass fiber base cloth to reduce porosity and surface roughness from the structure, and improve the uniformity of the coated polytetrafluoroethylene dispersion. At the same time, by adding a fluorine-containing surface active leveling agent to reduce the surface tension of the dispersion, the spreading ability of the coating is improved, and the accumulation and defect phenomenon is reduced. By adding a micro / nano closed / skeletal modifier to fill the pores of the fiber base cloth, the dispersion is limited from excessive penetration, and a stable micro / nano skeletal structure is formed during the sintering process, enhancing the mechanical strength and wear resistance of the coating. The synergistic effect of the two additives optimizes the surface and internal structure of the coating from the aspects of "flow-spreading" and "closure-skeleton", not only reducing the amount of polytetrafluoroethylene, but also improving the uniformity, heat resistance and mechanical properties of the coating.

[0006] To achieve the above object, the present application adopts the following technical solutions:

[0007] In a first aspect, the present application provides a preparation method of a polytetrafluoroethylene coated glass fiber cloth, which comprises:

[0008] S1: winding, arranging and twisting glass fibers to obtain yarn, weaving to obtain a target warp-weft density glass fiber base cloth, coating a sizing agent silane coupling agent solution on the surface of the glass fiber base cloth, drying and then heat setting to obtain a modified glass fiber base cloth;

[0009] S2: mixing polytetrafluoroethylene concentrated dispersion liquid with deionized water, adding fluorine-containing surface active leveling agent and micro-nano encapsulation / skeleton modifier to obtain a premixed dispersion liquid, adjusting pH, uniformly ultrasonic dispersing, standing, defoaming to obtain a modified polytetrafluoroethylene dispersion liquid;

[0010] S3: soaking the modified glass fiber base cloth in the modified polytetrafluoroethylene dispersion liquid, taking out and then pre-drying, followed by drying and sintering, and cooling to obtain a polytetrafluoroethylene coated glass fiber cloth;

[0011] The preparation method of the fluorine-containing surface active leveling agent is:

[0012] Dispersing perfluoropolyether diol in a mixed solvent, adding hexamethylene diisocyanate and dibutyl tin dilaurate to obtain reaction liquid A, reacting at constant temperature to obtain reaction liquid B, adding 1H, 1H, 2H, 2H-perfluorooctanol and continuing to react to obtain reaction liquid C, cooling, and distilling under reduced pressure to obtain the fluorine-containing surface active leveling agent;

[0013] The preparation method of the micro-nano encapsulation / skeleton modifier is:

[0014] Configuring an ethanol suspension of silicon dioxide, adding KH-570 to obtain a pre-modified dispersion liquid, adjusting pH with ammonia water, continuing to stir to obtain reaction liquid D, adding zirconium dioxide sol and continuing to stir to obtain reaction liquid E, and distilling under reduced pressure to obtain the micro-nano encapsulation / skeleton modifier;

[0015] As a preferred technical solution of the present application, in step S1, the diameter of the glass fiber is 9-13 μm, for example, it can be 9 μm, 9.4 μm, 9.8 μm, 10.2 μm, 10.6 μm, 11 μm, 11.4 μm, 11.8 μm, 12.2 μm, 12.6 μm or 13 μm, but is not limited to the listed values, and other values not listed in this range are also applicable.

[0016] In some optional embodiments, the yarn has a twist of 60-80 twists per meter, such as 60 twists per meter, 62 twists per meter, 64 twists per meter, 66 twists per meter, 68 twists per meter, 70 twists per meter, 72 twists per meter, 74 twists per meter, 76 twists per meter, 78 twists per meter, or 80 twists per meter, but is not limited to the listed values, and other values not listed within this range are also applicable.

[0017] In some optional embodiments, the target warp density of the glass fiber base cloth is 10-14 per cm, such as 10 per cm, 10.4 per cm, 10.8 per cm, 11.2 per cm, 11.6 per cm, 12 per cm, 12.4 per cm, 12.8 per cm, 13.2 per cm, 13.6 per cm, or 14 per cm, but is not limited to the listed values, and other values not listed within this range are also applicable.

[0018] In some optional embodiments, the target weft density of the glass fiber base cloth is 8-12 per cm, such as 8 per cm, 8.4 per cm, 8.8 per cm, 9.2 per cm, 9.6 per cm, 10 per cm, 10.4 per cm, 10.8 per cm, 11.2 per cm, 11.6 per cm, or 12 per cm, but is not limited to the listed values, and other values not listed within this range are also applicable.

[0019] In some optional embodiments, the mass fraction of the sizing agent silane coupling agent solution is 0.5-1.5 wt.%, such as 0.5 wt.%, 0.6 wt.%, 0.7 wt.%, 0.8 wt.%, 0.9 wt.%, 1.0 wt.%, 1.1 wt.%, 1.2 wt.%, 1.3 wt.%, 1.4 wt.%, or 1.5 wt.%, but is not limited to the listed values, and other values not listed within this range are also applicable.

[0020] As a preferred technical solution of the present application, in step S2, the mass ratio of the polytetrafluoroethylene concentrated dispersion solution to deionized water is 100:20-40, such as 100:20, 100:22, 100:24, 100:26, 100:28, 100:30, 100:32, 100:34, 100:36, 100:38, or 100:40, but is not limited to the listed values, and other values not listed within this range are also applicable.

[0021] In some alternative embodiments, the fluorine-containing surface active leveling agent is added in an amount of 0.5-1.5% by mass of the polytetrafluoroethylene concentrated dispersion, such as 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, or 1.5%, but not limited to the listed values, and other values within the range are also applicable.

[0022] In some alternative embodiments, the micro-nano encapsulation / skeleton modifier is added in an amount of 3-5% by mass of the polytetrafluoroethylene concentrated dispersion, such as 3%, 3.2%, 3.4%, 3.6%, 3.8%, 4%, 4.2%, 4.4%, 4.6%, 4.8%, or 5%, but not limited to the listed values, and other values within the range are also applicable.

[0023] In some alternative embodiments, the pH of the premixed dispersion is adjusted to 7-9, such as 7, 7.2, 7.4, 7.6, 7.8, 8, 8.2, 8.4, 8.6, 8.8, or 9, but not limited to the listed values, and other values within the range are also applicable.

[0024] As a preferred technical solution of the present application, in step S3, the modified glass fiber base fabric is soaked in the modified polytetrafluoroethylene dispersion for 1-2 min, such as 1 min, 1.1 min, 1.2 min, 1.3 min, 1.4 min, 1.5 min, 1.6 min, 1.7 min, 1.8 min, 1.9 min, or 2 min, but not limited to the listed values, and other values within the range are also applicable.

[0025] In some alternative embodiments, the pre-drying temperature is 60-80°C, such as 60°C, 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C, 76°C, 78°C, or 80°C, but not limited to the listed values, and other values within the range are also applicable.

[0026] In some alternative embodiments, the pre-drying time is 5-10 min, such as 5 min, 5.5 min, 6 min, 6.5 min, 7 min, 7.5 min, 8 min, 8.5 min, 9 min, 9.5 min, or 10 min, but not limited to the listed values, and other values within the range are also applicable.

[0027] In some optional embodiments, the drying temperature is 120-140℃, for example, it can be 120℃, 122℃, 124℃, 126℃, 128℃, 130℃, 132℃, 134℃, 136℃, 138℃ or 140℃, but not only limited to the listed values, other values in the range of values are also applicable.

[0028] In some optional embodiments, the drying time is 10-20min, for example, it can be 10min, 11min, 12min, 13min, 14min, 15min, 16min, 17min, 18min, 19min or 20min, but not only limited to the listed values, other values in the range of values are also applicable.

[0029] In some optional embodiments, the sintering temperature is 350-380℃, for example, it can be 350℃, 353℃, 356℃, 359℃, 362℃, 365℃, 368℃, 371℃, 374℃, 377℃ or 380℃, but not only limited to the listed values, other values in the range of values are also applicable.

[0030] In some optional embodiments, the sintering time is 10-20min, for example, it can be 10min, 11min, 12min, 13min, 14min, 15min, 16min, 17min, 18min, 19min or 20min, but not only limited to the listed values, other values in the range of values are also applicable.

[0031] As a preferred technical solution of the present application, in the preparation method of the fluorine-containing surface active leveling agent, the volume ratio of cyclohexanone to 1,4-dioxane in the mixed solvent is 1:1-2, for example, it can be 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9 or 1:2, but not only limited to the listed values, other values in the range of values are also applicable.

[0032] The number average molecular weight of the perfluoropolyether diol is 1000;

[0033] In some optional embodiments, the solid content of the perfluoropolyether diol dispersed in the mixed solvent is 10-20%, for example, it can be 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%, but not only limited to the listed values, other values in the range of values are also applicable.

[0034] In some optional embodiments, the molar ratio of the hexamethylene diisocyanate to the perfluoropolyether diol is 1-1.2:0.5, which can be, for example, 1:0.5, 1.02:0.5, 1.04:0.5, 1.06:0.5, 1.08:0.5, 1.1:0.5, 1.12:0.5, 1.14:0.5, 1.16:0.5, 1.18:0.5, or 1.2:0.5, but is not limited to the listed values, and other non-listed values within the range are also applicable.

[0035] In some optional embodiments, the amount of dibutyltin dilaurate used is 0.05-0.1% of the mass of the reaction solution A, which can be, for example, 0.05%, 0.055%, 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%, 0.09%, 0.095%, or 0.1%, but is not limited to the listed values, and other non-listed values within the range are also applicable.

[0036] In some optional embodiments, the temperature for the constant-temperature reaction of the reaction solution A is 60-80°C, which can be, for example, 60°C, 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C, 76°C, 78°C, or 80°C, but is not limited to the listed values, and other non-listed values within the range are also applicable.

[0037] In some optional embodiments, the time for the constant-temperature reaction of the reaction solution A is 2-4h, which can be, for example, 2h, 2.2h, 2.4h, 2.6h, 2.8h, 3h, 3.2h, 3.4h, 3.6h, 3.8h, or 4h, but is not limited to the listed values, and other non-listed values within the range are also applicable.

[0038] In some optional embodiments, the amount of 1H, 1H, 2H, 2H-perfluorooctanol used is 1-2% of the mass of the perfluoropolyether diol, which can be, for example, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, or 2%, but is not limited to the listed values, and other non-listed values within the range are also applicable.

[0039] In some optional embodiments, the reaction of the reaction solution B continues for 1-2h after the addition of the 1H, 1H, 2H, 2H-perfluorooctanol, which can be, for example, 1h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, or 2h, but is not limited to the listed values, and other non-listed values within the range are also applicable.

[0040] In some optional embodiments, the solid content of the fluorine-containing surface active leveling agent is 30-40%, for example, it can be 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39% or 40%, but not limited to the listed values, and other values not listed in the range are also applicable.

[0041] As a preferred technical solution of the present application, in the preparation method of the micro-nano encapsulation / skeleton modifier, the mass-volume ratio of the silica to ethanol is 5-10 g / 100-200 mL, for example, it can be 5 g / 100 mL, 5.5 g / 120 mL, 6 g / 140 mL, 6.5 g / 160 mL, 7 g / 180 mL, 7.5 g / 200 mL, 8 g / 120 mL, 8.5 g / 140 mL, 9 g / 160 mL, 9.5 g / 180 mL or 10 g / 200 mL, but not limited to the listed values, and other values not listed in the range are also applicable.

[0042] In some optional embodiments, the feeding amount of KH-570 is 5-15% of the mass of silica, for example, it can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% or 15%, but not limited to the listed values, and other values not listed in the range are also applicable.

[0043] In some optional embodiments, the pre-modification dispersion is adjusted to a pH of 8-10 using ammonia water, for example, it can be 8, 8.2, 8.4, 8.6, 8.8, 9, 9.2, 9.4, 9.6, 9.8 or 10, but not limited to the listed values, and other values not listed in the range are also applicable.

[0044] In some optional embodiments, after adjusting the pH of the pre-modification dispersion, stirring is continued for 1-2 h, for example, it can be 1 h, 1.1 h, 1.2 h, 1.3 h, 1.4 h, 1.5 h, 1.6 h, 1.7 h, 1.8 h, 1.9 h or 2 h, but not limited to the listed values, and other values not listed in the range are also applicable.

[0045] In some optional embodiments, the feeding amount of the zirconium dioxide sol is 20-30% of the mass of silica, for example, it can be 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29% or 30%, but not limited to the listed values, and other values not listed in the range are also applicable.

[0046] In some optional embodiments, the reaction solution D continues to be stirred for 1-2 hours after the zirconium dioxide sol is added, for example, it can be 1 hour, 1.1 hour, 1.2 hour, 1.3 hour, 1.4 hour, 1.5 hour, 1.6 hour, 1.7 hour, 1.8 hour, 1.9 hour or 2 hours, but not only limited to the listed values, other values not listed in the range are also applicable.

[0047] In some optional embodiments, the solid content of the micro-nano encapsulation / skeleton modifier is 20-30%, for example, it can be 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29% or 30%, but not only limited to the listed values, other values not listed in the range are also applicable.

[0048] In a second aspect, the present application provides a polytetrafluoroethylene coated glass fiber cloth.

[0049] The present application modifies the glass fiber base cloth from three dimensions of fiber diameter size, yarn twist, and weaving density.

[0050] The fiber diameter has a direct impact on the porosity and surface roughness of the glass fiber cloth. The larger the fiber diameter, the larger the gap between the fibers, resulting in an increase in porosity, which in turn makes the polytetrafluoroethylene dispersion easily penetrate too much during the coating process, causing material waste. In the present application, glass fibers with a diameter of 9-13 μm are selected for weaving. Smaller diameter glass fibers can effectively reduce the gap between the fibers, reduce the porosity, and improve the density of the base cloth; and finer fibers help to form a smooth surface, providing a more uniform substrate for coating polytetrafluoroethylene dispersion, reducing coating accumulation caused by surface tension differences.

[0051] Yarn twist affects the tightness and surface morphology of the fiber. If the twist is too small, the fibers are arranged loosely, the porosity of the base cloth increases, causing the polytetrafluoroethylene dispersion to easily penetrate into the interior during coating, increasing the material usage; too high twist may cause the surface to be uneven, increasing the surface roughness and reducing the coating uniformity. In the present application, a twist of 60-80 twists per meter is selected to ensure the tight arrangement of the yarn, reduce the gap between the fibers, and maintain the surface flatness, providing a better substrate for coating; at the same time, the control of twist can also optimize the mechanical properties of the glass fiber base cloth, avoiding deformation caused by stretching in subsequent processing.

[0052] The weaving density directly affects the overall porosity of the base cloth. If the weaving density is low, the porosity increases, and the polytetrafluoroethylene dispersion liquid can easily penetrate to a deeper level during coating, resulting in increased material usage. At the same time, the uniformity of the coating is also affected. If the density is too high, it can lead to a decrease in the flexibility of the base cloth, which is not conducive to subsequent processing. In this application, the weaving density is 10-14 warp yarns / cm and 8-12 weft yarns / cm. This setting can balance low porosity and flexibility. Such a fiber weaving structure not only reduces the penetration depth of the polytetrafluoroethylene dispersion liquid, but also helps to improve the uniformity of the coating. At the same time, reasonable control of the density can also optimize the surface flatness of the fiber base cloth and reduce surface roughness caused by weaving gaps.

[0053] In addition, in this application, a fluorine-containing surface active leveling agent and a micro-nano sealing / skeleton modifier are added to the polytetrafluoroethylene dispersion liquid for modification.

[0054] The high viscosity and poor wettability of the polytetrafluoroethylene dispersion liquid can lead to insufficient flowability during coating, uneven coating, and even local accumulation, increasing the material usage per unit area. At the same time, the difference in surface tension of the coating can cause coating shrinkage or bubbling, affecting the density and uniformity of the coating.

[0055] In this application, the fluorine-containing surface active leveling agent reduces the surface tension of the polytetrafluoroethylene dispersion liquid, improving the spreading ability of the dispersion liquid on the glass fiber base cloth, allowing it to be evenly distributed on the entire surface and avoiding coating accumulation caused by local high viscosity. After improving the leveling, the coating surface is smoother, reducing waste caused by surface defects during subsequent sintering. Further reducing the amount of polytetrafluoroethylene can also improve the apparent quality and chemical resistance of the coating.

[0056] The porous structure and high porosity of the glass fiber base cloth make it prone to excessive penetration when immersed in the polytetrafluoroethylene dispersion liquid, resulting in material waste. During the sintering process of the coating, the polytetrafluoroethylene particles may collapse due to lack of support, reducing the coating film strength and wear resistance.

[0057] The micro-nano sealing / skeleton modifier introduces silica and zirconia nanoparticles, filling the pores of the glass fiber base cloth during coating, reducing the penetration depth of the polytetrafluoroethylene dispersion liquid, and effectively saving material. During sintering, the micro-nano structure skeleton formed by silica and zirconia enhances the mechanical strength of the coating, improving the wear resistance and high temperature resistance of the coating. At the same time, the micro-nano sealing / skeleton modifier also forms a stable support structure inside the coating, preventing deformation or collapse of the coating during high temperature sintering.

[0058] There is also a synergistic effect between the fluorine-containing surface active leveling agent and the micro-nano sealing / skeleton modifier. The fluorine-containing surface active leveling agent improves the uniformity and leveling of the surface layer coating, enabling the coating to form a continuous and uniform thin layer on the surface of the base fabric before sintering. The micro-nano sealing / skeleton modifier limits the excessive penetration of the polytetrafluoroethylene dispersion liquid in the coating through filling and strengthening, and provides strong mechanical support after sintering. The two synergistically control the two key processes of “flow-spreading” and “sealing-skeleton” during coating.

[0059] Secondly, the fluorine-containing surface active leveling agent reduces the coating accumulation, and the micro-nano sealing / skeleton modifier limits the coating penetration. Through synergistic effect, the amount of polytetrafluoroethylene is reduced under the premise of ensuring the quality of the coating. The synergistic effect of the two optimizes the surface and internal structure of the coating, reduces defects caused by uneven surface coating, and enhances the heat resistance and mechanical strength of the coating.

[0060] Compared with the prior art, the application has the following beneficial effects:

[0061] The application modifies the glass fiber base fabric by controlling three dimensions of fiber diameter, yarn twist and weaving density to reduce porosity, reduce surface roughness and improve the uniformity of coating polytetrafluoroethylene dispersion liquid. The glass fiber with a diameter of 9-13 μm can effectively reduce the fiber gap and porosity, and form a smooth surface to reduce coating accumulation. The twist is set to 60-80 twists per meter, which can ensure the close arrangement and surface flatness of the yarn, and help to avoid excessive penetration or roughness caused by loose or tight. The weaving density is 10-14 ends / cm for warp and 8-12 ends / cm for weft. This structure reduces the deep penetration of polytetrafluoroethylene dispersion liquid, and also takes into account the flexibility and flatness of the base fabric, thereby providing an ideal substrate for the uniformity and performance of the coating;

[0062] The polytetrafluoroethylene dispersion liquid may cause insufficient flowability, uneven distribution, and even local accumulation due to high viscosity and poor wettability, increasing the amount of material and causing defects such as shrinkage and blistering, affecting the density and uniformity of the coating. The application adds a fluorine-containing surface active leveling agent to effectively reduce the surface tension of the dispersion liquid, improve its spreading ability on the glass fiber base fabric, ensure uniform coating, and avoid accumulation. The modified coating surface is smoother, reducing surface defects during sintering, reducing the amount of polytetrafluoroethylene, and improving the apparent quality and chemical resistance of the coating;

[0063] Glass fiber fabric is prone to excessive penetration when immersed in polytetrafluoroethylene dispersion due to its porous structure and high porosity, resulting in material waste. Meanwhile, the lack of support during sintering can lead to coating collapse, reducing strength and wear resistance. By adding micro / nano encapsulation / skeleton modifier, this application introduces silica and zirconium dioxide nanoparticles to fill the fabric pores during coating, reducing the penetration depth of the dispersion and effectively saving materials. During sintering, these nanoparticles form a micro / nano skeleton, enhancing the mechanical strength and wear resistance of the coating through cross-linking, and forming a stable support structure inside the coating to prevent deformation or collapse during high-temperature sintering, thereby improving the overall performance of the coating.

[0064] The fluorine-containing surface active leveling agent and the micro / nano encapsulation / skeleton modifier have a synergistic effect. The former improves the leveling and uniformity of the coating, allowing the polytetrafluoroethylene dispersion to form a continuous thin layer on the surface of the fabric before sintering. The latter limits the excessive penetration of the dispersion by filling the pores and strengthening the internal structure, and provides mechanical support after sintering. The two key links of "flow-spreading" and "encapsulation-skeleton" during coating are synergistically controlled, not only reducing the accumulation and penetration of the coating, but also reducing the amount of polytetrafluoroethylene, while optimizing the surface and internal structure of the coating, reducing defects and enhancing the heat resistance and mechanical strength of the coating. DETAILED DESCRIPTION

[0065] The technical solutions of the present application will be described in detail below in conjunction with specific examples. The examples described herein are specific embodiments of the present application, which are used to illustrate the concept of the present application; these descriptions are explanatory and exemplary, and should not be understood as limiting the embodiments of the present application and the scope of protection of the present application. In addition to the examples described herein, those skilled in the art can also use other technical solutions that are obvious based on the disclosure of the claims and the specification of the present application, including technical solutions that make any obvious substitutions and modifications to the examples described herein.

[0066] The chemical reagents used in the examples and comparative examples of the present application are commercially available and have not been further purified or treated.

[0067] Example 1

[0068] The present embodiment provides a polytetrafluoroethylene coated glass fiber fabric and a method for preparing the same. The method for preparing the polytetrafluoroethylene coated glass fiber fabric specifically includes the following steps:

[0069] S1: winding, arranging and twisting glass fibers with a diameter of 12 μm to obtain yarns, weaving to obtain a target warp-weft density glass fiber base cloth, wherein the twist of the yarns is 70 twists per meter, the warp density of the target warp-weft density glass fiber base cloth is 13 roots / cm, and the weft density of the target warp-weft density glass fiber base cloth is 10 roots / cm; coating a silane coupling agent solution with a mass fraction of 1.0 wt.% on the surface of the glass fiber base cloth, and heat setting after drying to obtain a modified glass fiber base cloth;

[0070] S2: mixing polytetrafluoroethylene concentrated dispersion liquid and deionized water at a mass ratio of 100:30, adding a fluorine-containing surface active leveling agent with a feeding amount of 1.2% of the mass of the polytetrafluoroethylene concentrated dispersion liquid and a micro-nano closed / skeleton modifier with a feeding amount of 4.5% of the mass of the polytetrafluoroethylene concentrated dispersion liquid to obtain a premixed dispersion liquid, adjusting the pH to 8.5, uniformly ultrasonic dispersing, standing and defoaming to obtain a modified polytetrafluoroethylene dispersion liquid;

[0071] S3: soaking the modified glass fiber base cloth in the modified polytetrafluoroethylene dispersion liquid for 1.8 min, pre-drying at 60°C for 5 min after taking out, then heating to 130°C for drying for 10 min, and sintering at 360°C for 18 min to obtain a polytetrafluoroethylene coated glass fiber cloth;

[0072] The preparation method of the fluorine-containing surface active leveling agent is as follows:

[0073] Dispersing perfluoropolyether diol in a mixed solvent, wherein the volume ratio of cyclohexanone to 1,4-dioxane in the mixed solvent is 1:1.5, the solid content of the perfluoropolyether diol dispersed in the mixed solvent is 18%, adding hexamethylene diisocyanate and dibutyltin dilaurate with a feeding amount of 0.08% of the mass of reaction liquid A to obtain reaction liquid A, wherein the molar ratio of hexamethylene diisocyanate to perfluoropolyether diol is 1.1:0.5, reacting at a constant temperature of 75°C for 3.4 h to obtain reaction liquid B, adding 1H,1H,2H,2H-perfluorooctanol with a feeding amount of 1.5% of the mass of perfluoropolyether diol to continue reacting for 1 h to obtain reaction liquid C, cooling and distilling under reduced pressure to obtain a fluorine-containing surface active leveling agent with a solid content of 30%;

[0074] The preparation method of the micro-nano closed / skeleton modifier is as follows:

[0075] Configuring an ethanol suspension of silicon dioxide, wherein the mass-volume ratio of silicon dioxide to ethanol is 8 g / 150 mL, adding KH-570 with a feeding amount of 10% of the mass of silicon dioxide to obtain a pre-modified dispersion liquid, adjusting the pH to 9.5 using ammonia water, and continuing to stir for 1.5 h to obtain reaction liquid D, adding zirconium dioxide sol with a feeding amount of 25% of the mass of silicon dioxide and continuing to stir for 1 h to obtain reaction liquid E, and distilling under reduced pressure to obtain a micro-nano closed / skeleton modifier with a solid content of 26%.

[0076] Example 2

[0077] The embodiment provides a polytetrafluoroethylene-coated glass fiber cloth and a preparation method thereof. The preparation method of the polytetrafluoroethylene-coated glass fiber cloth specifically comprises the following steps:

[0078] S1: winding, arranging and twisting glass fibers with a diameter of 9 μm to obtain yarn, and weaving to obtain a target warp-weft density glass fiber base cloth, wherein the twist of the yarn is 75 twists per meter, the warp density of the target warp-weft density glass fiber base cloth is 10 roots / cm, and the weft density of the target warp-weft density glass fiber base cloth is 8 roots / cm; coating a sizing agent silane coupling agent solution with a mass fraction of 0.5 wt.% on the surface of the glass fiber base cloth, and heat setting after drying to obtain a modified glass fiber base cloth;

[0079] S2: mixing polytetrafluoroethylene concentrated dispersion liquid and deionized water at a mass ratio of 100:35, adding a fluorine-containing surface active leveling agent with a feeding amount of 1.0% of the mass of the polytetrafluoroethylene concentrated dispersion liquid and a micro-nano closed / skeleton modifier with a feeding amount of 4% of the mass of the polytetrafluoroethylene concentrated dispersion liquid to obtain a premixed dispersion liquid, adjusting the pH to 7, uniformly ultrasonic dispersing, and then standing and defoaming to obtain a modified polytetrafluoroethylene dispersion liquid;

[0080] S3: soaking the modified glass fiber base cloth in the modified polytetrafluoroethylene dispersion liquid for 1.5 min, taking out and pre-drying at 70°C for 8 min, then heating to 120°C for drying for 18 min, and sintering at 370°C for 10 min to obtain a polytetrafluoroethylene-coated glass fiber cloth;

[0081] The preparation method of the fluorine-containing surface active leveling agent is as follows:

[0082] Dispersing perfluoropolyether diol in a mixed solvent, wherein the volume ratio of cyclohexanone to 1,4-dioxane in the mixed solvent is 1:1.8, the solid content of the perfluoropolyether diol dispersed in the mixed solvent is 10%, adding hexamethylene diisocyanate and dibutyltin dilaureate with a feeding amount of 0.05% of the mass of the reaction liquid A to obtain reaction liquid A, wherein the molar ratio of hexamethylene diisocyanate to perfluoropolyether diol is 1.16:0.5, reacting at a constant temperature of 60°C for 2 h to obtain reaction liquid B, adding 1H,1H,2H,2H-perfluorooctanol with a feeding amount of 1.8% of the mass of the perfluoropolyether diol to continue reacting for 1.4 h to obtain reaction liquid C, cooling, and distilling under reduced pressure to obtain the fluorine-containing surface active leveling agent with a solid content of 35%;

[0083] The preparation method of the micro-nano closed / skeleton modifier is as follows:

[0084] An ethanol suspension of silicon dioxide was configured, wherein the mass-volume ratio of silicon dioxide to ethanol was 7 g / 170 mL, a pre-modification dispersion was obtained by adding KH-570 in an amount of 5% of the mass of silicon dioxide, the pH was adjusted to 8 using ammonia water, and stirring was continued for 1.8 h to obtain reaction liquid D, zirconium dioxide sol was added in an amount of 28% of the mass of silicon dioxide, and stirring was continued for 1.6 h to obtain reaction liquid E, and vacuum distillation was performed to obtain a micro-nano encapsulation / skeleton modifier with a solid content of 28%.

[0085] Example 3

[0086] The embodiment provides a polytetrafluoroethylene-coated glass fiber cloth and a preparation method thereof. The preparation method of the polytetrafluoroethylene-coated glass fiber cloth specifically comprises the following steps:

[0087] S1: Glass fibers with a diameter of 11 μm are wound, arranged and twisted to obtain yarns, and the yarns are woven to obtain a target warp-weft density glass fiber base cloth, wherein the twist of the yarns is 60 twists per meter, the warp density of the target warp-weft density glass fiber base cloth is 12 roots / cm, and the weft density of the target warp-weft density glass fiber base cloth is 12 roots / cm; a sizing agent silane coupling agent solution with a mass fraction of 1.2 wt.% is coated on the surface of the target warp-weft density glass fiber base cloth, and the target warp-weft density glass fiber base cloth is heat set after drying to obtain a modified glass fiber base cloth;

[0088] S2: A polytetrafluoroethylene concentrated dispersion liquid is mixed with deionized water at a mass ratio of 100:20, a fluorine-containing surface active leveling agent is added in an amount of 0.5% of the mass of the polytetrafluoroethylene concentrated dispersion liquid, and a micro-nano encapsulation / skeleton modifier is added in an amount of 3% of the mass of the polytetrafluoroethylene concentrated dispersion liquid to obtain a premix dispersion liquid, the pH is adjusted to 8, and the modified polytetrafluoroethylene dispersion liquid is obtained after ultrasonic dispersion, standing and defoaming;

[0089] S3: The modified glass fiber base cloth is soaked in the modified polytetrafluoroethylene dispersion liquid for 1 min, and then taken out and pre-dried at 75°C for 9 min, and then heated to 135°C for drying for 20 min, sintered at 350°C for 20 min, and cooled to obtain a polytetrafluoroethylene-coated glass fiber cloth;

[0090] The preparation method of the fluorine-containing surface active leveling agent is as follows:

[0091] The perfluoropolyether diol is dispersed in a mixed solvent, the volume ratio of cyclohexanone to 1, 4-dioxane in the mixed solvent is 1:1, the solid content of the perfluoropolyether diol dispersed in the mixed solvent is 16%, hexamethylene diisocyanate and dibutyltin dilaurate with a dosage of 0.09% of the mass of the reaction liquid A are added to obtain a reaction liquid A, the molar ratio of hexamethylene diisocyanate to perfluoropolyether diol is 1:0.5, the reaction is carried out at a constant temperature of 70℃ for 3h to obtain a reaction liquid B, 1H, 1H, 2H, 2H-perfluorooctanol with a dosage of 1% of the mass of the perfluoropolyether diol is added to continue the reaction for 2h to obtain a reaction liquid C, and cooling and reduced pressure distillation are carried out to obtain a fluorine-containing surfactant leveling agent with a solid content of 38%;

[0092] The preparation method of the micro-nano closed / skeleton modifier is as follows:

[0093] An ethanol suspension of silica is configured, the mass-volume ratio of silica to ethanol is 5g / 100mL, KH-570 with a dosage of 12% of the mass of the silica is added to obtain a pre-modified dispersion, ammonia is used to adjust the pH to 9, and stirring is continued for 1h to obtain a reaction liquid D, zirconium dioxide sol with a dosage of 20% of the mass of the silica is added and stirring is continued for 2h to obtain a reaction liquid E, and reduced pressure distillation is carried out to obtain a micro-nano closed / skeleton modifier with a solid content of 20%.

[0094] Example 4

[0095] The embodiment provides a polytetrafluoroethylene coated glass fiber cloth and a preparation method thereof, and the preparation method of the polytetrafluoroethylene coated glass fiber cloth specifically comprises the following steps:

[0096] S1: Glass fibers with a diameter of 13μm are wound, arranged and twisted to obtain yarns, and the yarns are woven to obtain a target warp-weft density glass fiber base cloth, wherein the twist of the yarns is 80 twists per meter, the warp density of the target warp-weft density glass fiber base cloth is 14 roots / cm, and the weft density of the target warp-weft density glass fiber base cloth is 11 roots / cm; a sizing agent silane coupling agent solution with a mass fraction of 1.5wt.% is coated on the surface of the glass fiber base cloth, and the glass fiber base cloth is heat set after drying to obtain a modified glass fiber base cloth;

[0097] S2: A polytetrafluoroethylene concentrated dispersion is mixed with deionized water at a mass ratio of 100:40, a fluorine-containing surfactant leveling agent with a dosage of 1.5% of the mass of the polytetrafluoroethylene concentrated dispersion and a micro-nano closed / skeleton modifier with a dosage of 5% of the mass of the polytetrafluoroethylene concentrated dispersion are added to obtain a premixed dispersion, the pH is adjusted to 9, and the polytetrafluoroethylene dispersion is uniformly dispersed by ultrasonic dispersion, and then the modified polytetrafluoroethylene dispersion is obtained by standing and defoaming;

[0098] S3: The modified glass fiber base cloth is soaked in the modified polytetrafluoroethylene dispersion liquid for 2 min, and after being taken out, it is pre-dried at 80℃ for 10 min, then heated to 140℃ for drying for 15 min, and sintered at 380℃ for 15 min, and cooled to obtain a polytetrafluoroethylene coated glass fiber cloth;

[0099] The preparation method of the fluorine-containing surface active leveling agent is:

[0100] The perfluoropolyether diol is dispersed in a mixed solvent, wherein the volume ratio of cyclohexanone to 1,4-dioxane in the mixed solvent is 1:2, the solid content of the perfluoropolyether diol dispersed in the mixed solvent is 20%, hexamethylene diisocyanate and 0.1% of dibutyltin dilaurate based on the mass of the reaction liquid A are added to obtain a reaction liquid A, wherein the molar ratio of hexamethylene diisocyanate to perfluoropolyether diol is 1.2:0.5, and the reaction is carried out at a constant temperature of 80℃ for 4h to obtain a reaction liquid B, then 2% of 1H,1H,2H,2H-perfluorooctanol based on the mass of the perfluoropolyether diol is added and the reaction is continued for 1.7h to obtain a reaction liquid C, and then cooling and reduced pressure distillation are carried out to obtain a fluorine-containing surface active leveling agent with a solid content of 40%;

[0101] The preparation method of the micro / nano closed / skeleton modifier is:

[0102] An ethanol suspension of silica is prepared, wherein the mass / volume ratio of silica to ethanol is 10g / 200mL, 15% of KH-570 based on the mass of the silica is added to obtain a pre-modified dispersion liquid, ammonia water is used to adjust the pH to 10, and the stirring is continued for 2h to obtain a reaction liquid D, 30% of zirconium dioxide sol based on the mass of the silica is added and the stirring is continued for 1.9h to obtain a reaction liquid E, and then reduced pressure distillation is carried out to obtain a micro / nano closed / skeleton modifier with a solid content of 30%.

[0103] Comparative Example 1

[0104] This comparative example provides a polytetrafluoroethylene coated glass fiber cloth, which is different from Example 1 in that in S2, no fluorine-containing surface active leveling agent is added, and the other operation steps and process parameters are exactly the same as those of Example 1.

[0105] Comparative Example 2

[0106] This comparative example provides a polytetrafluoroethylene coated glass fiber cloth, which is different from Example 1 in that in S2, no micro / nano closed / skeleton modifier is added, and the other operation steps and process parameters are exactly the same as those of Example 1.

[0107] The polytetrafluoroethylene coated glass fiber cloths of Examples 1-4 and Comparative Examples 1-2 are tested for performance, and the specific process is as follows:

[0108] The modified glass fiber base cloth obtained in S1 was cut into the same size (10 x 10 cm 2 ), and the mass of the blank base cloth was recorded as m0. Then, the base cloth was soaked, and the mass after soaking was recorded as m1. The PTFE dosage per unit area was calculated:

[0109] PTFE dosage per unit area = (m1-m0) / base cloth area

[0110] Mechanical properties: tensile strength test was performed by a universal material testing machine.

[0111] Heat resistance: the sample was placed in a high temperature environment of 500°C, and the size change was observed.

[0112] The test results are shown in Table 1.

[0113] Table 1: Performance test results of polytetrafluoroethylene coated glass fiber cloth of Examples 1-4 and Comparative Examples 1-2

[0114]

[0115] From the test results of Example 1 and Comparative Example 1, it can be seen that the absence of fluorine-containing surface active leveling agent leads to a decrease in the wettability of the polytetrafluoroethylene dispersion, which cannot uniformly spread on the substrate surface. During the coating process, a discontinuous liquid film is formed, and some areas are exposed due to poor wetting, which requires increasing the coating amount to compensate for the coverage, thereby increasing the polytetrafluoroethylene dosage per unit area; the uneven coating causes interface defects (such as micro-holes and thickness mutations), and under external force, stress is concentrated at the defects, and cracks preferentially initiate and expand from these weak areas. At the same time, the orientation degree of the polytetrafluoroethylene molecular chain is reduced due to insufficient leveling, which weakens the carrying capacity of the material in the stress direction; the difference in the local coefficient of thermal expansion of the non-uniform coating leads to uneven distribution of thermal stress. When heated, the difference in expansion amount between the thick coating area and the thin coating area forms internal shear stress, which promotes the overall distortion of the material, and the dimensional stability deteriorates.

[0116] From the test results of Example 1 and Comparative Example 2, the absence of the micro-nano sealing / skeleton modifier makes the substrate surface pores not effectively sealed, and the polytetrafluoroethylene melt penetrates into the substrate pores during processing. This ineffective penetration consumes a large amount of resin but cannot form effective interfacial bonding, resulting in insufficient effective resin amount of the actual functional coating, which needs to be additionally coated to meet the performance requirements; the absence of the micro-nano sealing / skeleton modifier leads to the lack of chemical bonding and physical anchoring between the fibers and the polytetrafluoroethylene, and the interface only relies on weak van der Waals force bonding. During load transfer, the fiber and the resin are prone to debonding, and the crack rapidly expands along the weak interface, and the overall load-carrying capacity of the material is greatly reduced; the absence of the micro-nano sealing / skeleton modifier makes the polytetrafluoroethylene matrix lose the rigid support when heated. At the same time, the difference in thermal expansion between the fiber and the resin causes the interface to peel off, and the cooperative deformation ability of the two is lost, resulting in the collapse of the overall thermal dimensional stability of the material.

[0117] The above merely provides a specific implementation of the present application, but the protection scope of the present application is not limited thereto. It should be understood by those skilled in the art that any changes or replacements within the technical scope disclosed by the present application can be easily conceived by those skilled in the art, and all such changes and replacements fall within the protection scope and disclosure scope of the present application.

Claims

1. A method for producing a polytetrafluoroethylene-coated glass fiber cloth, characterized by, The preparation method comprises: S1: winding, arranging and twisting the glass fibers to obtain a yarn, weaving to obtain a target warp-weft density glass fiber base cloth, coating a sizing agent silane coupling agent solution on the surface of the target warp-weft density glass fiber base cloth, and drying and heat setting to obtain a modified glass fiber base cloth; S2: mixing polytetrafluoroethylene concentrated dispersion liquid and deionized water, adding a fluorine-containing surface active leveling agent and a micro-nano encapsulation / skeleton modifier to obtain a premixed dispersion liquid, adjusting the pH, uniformly ultrasonic dispersing, standing, and defoaming to obtain a modified polytetrafluoroethylene dispersion liquid; S3: soaking the modified glass fiber base cloth in the modified polytetrafluoroethylene dispersion liquid, taking out and pre-drying, then drying and sintering, and cooling to obtain a polytetrafluoroethylene coated glass fiber cloth; The preparation method of the fluorine-containing surface active leveling agent is as follows: dispersing perfluoropolyether diol in a mixed solvent, adding hexamethylene diisocyanate and dibutyl tin dilaurate to obtain reaction liquid A, reacting at a constant temperature to obtain reaction liquid B, continuously reacting after adding 1H, 1H, 2H, 2H-perfluorooctanol to obtain reaction liquid C, cooling, and distilling under reduced pressure to obtain the fluorine-containing surface active leveling agent; The preparation method of the micro-nano encapsulation / skeleton modifier is as follows: configuring an ethanol suspension of silicon dioxide, adding KH-570 to obtain a pre-modified dispersion liquid, adjusting the pH with ammonia water, continuously stirring to obtain reaction liquid D, adding zirconium dioxide sol and continuously stirring to obtain reaction liquid E, and distilling under reduced pressure to obtain the micro-nano encapsulation / skeleton modifier.

2. The method for preparing a polytetrafluoroethylene-coated glass fiber cloth according to claim 1, characterized in that, In S1: the diameter of the glass fiber is 9-13 μm; the twist of the yarn is 60-80 twists per meter; the warp density of the target warp-weft density glass fiber base cloth is 10-14 roots / cm; the weft density of the target warp-weft density glass fiber base cloth is 8-12 roots / cm.

3. The method for preparing a polytetrafluoroethylene-coated glass fiber cloth according to claim 1, characterized in that, In S2: the mass ratio of the polytetrafluoroethylene concentrated dispersion liquid to deionized water is 100:20-40; the feeding amount of the fluorine-containing surface active leveling agent is 0.5-1.5% of the mass of the polytetrafluoroethylene concentrated dispersion liquid; the feeding amount of the micro-nano encapsulation / skeleton modifier is 3-5% of the mass of the polytetrafluoroethylene concentrated dispersion liquid.

4. The method for preparing a polytetrafluoroethylene-coated glass fiber cloth according to claim 1, characterized in that, In the preparation method of the fluorine-containing surface active leveling agent: the volume ratio of cyclohexanone to 1,4-dioxane in the mixed solvent is 1:1-2; the molar ratio of hexamethylene diisocyanate to perfluoropolyether diol is 1-1.2:0.5; the feeding amount of 1H, 1H, 2H, 2H-perfluorooctanol is 1-2% of the mass of the perfluoropolyether diol; the solid content of the fluorine-containing surface active leveling agent is 30-40%.

5. The method for preparing a polytetrafluoroethylene-coated glass fiber cloth according to claim 1, characterized in that, In the preparation method of the micro-nano encapsulation / skeleton modifier: the mass-volume ratio of the silicon dioxide to ethanol is 5-10 g / 100-200 mL; the feeding amount of the KH-570 is 5-15% of the mass of the silicon dioxide; the feeding amount of the zirconium dioxide sol is 20-30% of the mass of the silicon dioxide; the solid content of the micro-nano encapsulation / skeleton modifier is 20-30%.

6. The method for preparing a polytetrafluoroethylene coated glass fiber cloth according to claim 1, characterized in that, In S3: the temperature of the pre-drying is 60-80℃; the time of the pre-drying is 5-10 min; the temperature of the drying is 120-140℃; the time of the drying is 10-20 min; The sintering temperature is 350-380℃; The sintering time is 10-20min.

7. A polytetrafluoroethylene coated glass fiber fabric prepared by the method according to any one of claims 1-6.

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